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64 lines
2.5 KiB
Markdown
64 lines
2.5 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/GAMMA/blob/master/LICENSE)
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[](https://github.com/RobTillaart/GAMMA/releases)
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# GAMMA
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Arduino Library for the GAMMA function to adjust brightness of LED's etc.
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## Description
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This library is provides a gamma lookup class. It is typical used to
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change the intensity / brightness of a LED to match the human eye.
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When a LED is given 50% PWM it looks far brighter for the eye.
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This lib provides a balance between an expensive math function and the speed
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of a lookup table.
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The accuracy of the library depends on the size of the internal array.
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A size of 256 is the reference. Smaller arrays use interpolation and
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these interpolated values are good (< 1%) down to internal array size 16.
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The size can be as small as 2 which is pretty inaccurate.
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In this latter case the curve is approximated by only two linear interpolations.
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In short, choose the size that fits your application.
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The library has a **setGamma()** function that allows an application to change
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the gamma value runtime. This allows adjustments that a fixed table does not have.
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The class can be used to dump the internal table e.g. to place in PROGMEM.
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## Interface
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### Core functions
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- **GAMMA(size = 32)** constructor, gets the size of the internal
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array as parameter. The array is initialized with a gamma == 2.8 which
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is an often used value.
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The default for size = 32 as this is a good balance between performance
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and size ot the internal array.
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The size parameter must be in {2, 4, 8, 16, 32, 64, 128, 256 }
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- **setGamma(float gamma)** calculates and fills the array with new values.
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This can be done runtime so runtime adjustment of gamma mapping.
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This function relative quite some time.
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- **getGamma()** returns the set gamma value.
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- **operator \[\]** allows the GAMMA object to be accessed as an array.
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like ```x = G[40];``` Makes it easy to switch with a real array.
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### Development functions
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- **size()** returns size of the internal array.
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- **distinct()** returns the number of distinct values in the table.
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- **dump()** dumps the internal table to Serial. Can be useful to create
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a direct usable array in RAM, PROGMEM or wherever.
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## Future ideas
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- look for optimizations
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- uint16 version?
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-
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## Operation
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See example
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